of the Mole-cricket. 4,23 



not be rejected without some previous attention to it With 

 regard to the dorsal vessel of the gryllotalpa, which iii this as 

 in other insects, has been supposed lo stand in the place of an 

 arterial heart, I have very few observations to offer. It does 

 not agree in its form with the description commonly o-iven of 

 this mysterious organ; for though it diminishes in diameter as 

 It approaches the head, this is by no means the case towards 

 the other extremity of it. I have not yet completely succeed- 

 ed in tracmg this vessel to its anterior extremity ; because as 

 it approaches its termination in that direction, it becomes so 

 delicate as to have hitherto broken under dissection before I 

 arrived at the extremity of it. Towards the opposite extremity 

 It gradually becomes larger from the centre of the body and 

 terminates apparently in a cul-de-sac about the last segment 

 bul two of the abdomen. * 



The muscles.— In the gryllotalpa, as in insects in general, 

 the muscles are exceedingly numerous, and usually very di- 

 stinctly defined ; but as their form and size in different parts 

 ot the body may, without difficulty, be conjectured froni the 

 torm and size of the parts to which they are appropriate, I 

 need not occupy the time of die Society by enumerating or 

 particularly describing them. Those which move the forelegs 

 are remarkable for their size, and apparently fill nearly the 

 whole of the interior of the thorax. Some muscles, as is the 

 case with two belonging to each mandible, and with some of 

 those that are situated within the thigh of the hind leg, have 

 tendons attached to them of considerable extent and streno-th 

 I must not omit to mention several parallel muscular bands 

 which run in a longitudinal direction along the outer coat of 

 the extremity of the great intestine, and are inserted into what 

 may- be called the sphincter of the rectum : these muscular 

 bands may evidently assist, by their previous contraction and 

 subsequent relaxation, in discharging that fetid matter which, 

 as has been already said, the animal usually emits when irri- 

 ?i^ ^xTu^^'' !?^ discovery of these muscles I am indebted to 

 Mr. Whessell, whose name I have before mentioned on a si- 

 milar occasion. 



The nerves*.--In removing the integuments throughout the 

 whole length of the lower surface of the body, we discover a 

 series of nine ganglions, of a pale cream-colour, dislributed at 

 unequal intervals from the commencement of the oesophaous to 

 the termination of the rectum ; a double medullary cord'beincr 

 continuecl from one ganglion to another throughout the whole 

 series. Ihe ganglions and their connecting cords he so nearly 



Vide Plate HI. figs. 1 1 ami 12. 



